3.2.2. Check-in function. Check-in function is a function
for indicating that the user has reached the check-in point.
Check-in point is the river administrator sets. By setting
the check-in point, it can be confirmed that someone has
reached its location. If there is a defect in the river basin,
citizens report a problem by the application to reach the site.
River administrator can confirm the defect. Not necessarily
that there is no trouble in not posted location. Users do not
post if there is no problem to reach the location. However,
it is not also posted if nobody reaches the location. Checkin
function is a function for checking whether the user has
arrived to no post location.